Abstract: Previous research on the vacuum consolidation behavior of dredged sludge havepredominantly been conducted using small-scale model tests, with limited attention given to radial deformation characteristics. To address this limitation, a full-scale model test was conducted under field conditions at a dredged sludge disposal site along the Wusong River in Kunshan, China. The test systematically examined the coupled evolution of vacuum pressure and water content, along with the radial deformation characteristics of the sludge. The results indicate that significant deformation occurred beneath the plastic vertical drain during vacuum preloading, which was identified as a key factor contributing to the marked reduction in vacuum pressure in this region. The onset of vacuum transmission within the sludge closely corresponded to the point at which the rate of water content reduction began to decrease, indicating a strong association between vacuum development and a critical water content threshold. In addition, the sludge exhibited pronounced radial shrinkage, with the magnitude of deformation diminishing exponentially with depth. These findings provide a basis for a deeper understanding of the vacuum consolidation mechanisms in dredged sludge.